Combustion of hydrocarbon fuels in internal-combustion engines is a major contributor to an increase in carbon dioxide content in Earth atmosphere, which according to prevailing scientific consensus contributes to global warming. It is also responsible for the ever increasing import of foreign oil, which adversely affects the national trade balance account. It is therefore imperative to achieve a substantial reduction in the amount of fuel consumed by internal-combustion engines on a national scale.
Most internal-combustion engines are used in ground transportation, and most vehicles driven on American roads use spark-ignition gasoline engines. Diesel engines offer a much better fuel economy than gasoline engines. Using a diesel instead of a gasoline engine, whenever possible, represents one of the most straightforward ways to achieve better fuel consumption and lower carbon dioxide emission. There are, however, some important reasons why usage of diesel engines is less prevalent than usage of gasoline engines. Diesel engines have some very significant deficiencies, some of which are listed below.
Diesels are prodigious producers of nitrogen oxides, which are considered to be some of the most harmful air pollutants. Controlling nitrogen oxides emission is very difficult and very expensive. Another drawback of diesels is emission of particulate matter, which is very harmful to human health. This too is difficult to control and adds significantly to the engine system cost and complexity. Diesel combustion process requires more air at peak power than a gasoline engine does. Because of that, diesel is substantially bigger and heavier than a comparable gasoline engine, unless its operation is boosted by induction of pressurized air. For this, most contemporary diesels use turbochargers, and this leads to a substantial increase in cost and complexity. These and some other drawbacks reduce the appeal of diesels to general public and prevent broader use of diesel engines in passenger vehicles despite their superior fuel economy.
In view of the above, it is clear that it is highly desirable to have a system and a method of internal-combustion engine operation that, when applied to diesel engines, eliminates the above disadvantages while retaining the fuel economy advantage. Such a system and a method are the subject of the present invention.